Structure and Phase Composition of Multilayer AlN/SiN Films Irradiated with Helium Ions

Abstract

The results of investigating the microstructure and phase composition of AlN/SiN_x multilayer films with alternating nanocrystalline aluminum nitride (nc-AlN) and amorphous silicon nitride (a-SiN_x) phases, which were formed via magnetron sputtering, are presented. The layer thickness varies from 2 to 10 nm, the total film thickness is 300 nm, and the grain size of the AlN phase corresponds to the nc-AlN layer thickness. By means of transmission electron microscopy, it is revealed that, due to 30-keV He⁺ ion irradiation with a dose of 5 × 10¹⁶ cm^–2, gas pores with an average size of 2.0–2.4 nm and localized mainly in a-SiN_x layers are generated within the projective range of helium ions. The appearance of such inclusions is due to the fact that implanted helium atoms migrate into the formed vacancy complexes. In this case, the structural state of AlN crystal layers remains unchanged.